How to use the fontbakery.utils.get_FamilyProto_Message function in fontbakery

## Step 1: Cross-family tests
##         * Validates consistency of data throughout all TTF files
##           in a given family
##         * The list of TTF files in infered from the METADATA.pb file
##         * We avoid testing the same family twice by deduplicating the
##           list of METADATA.pb files first
###########################################################################

  metadata_to_check = []
  for target in fonts_to_check:
    metadata = os.path.join(family_dir, "METADATA.pb")
    if not os.path.exists(metadata):
      logging.error("'{}' is missing"
                    " a METADATA.pb file!".format(target))
    else:
      family = get_FamilyProto_Message(metadata)
      if family is None:
        logging.warning("Could not load data from METADATA.pb.")
      elif family not in metadata_to_check:
        metadata_to_check.append([family_dir, family])

  for dirname, family in metadata_to_check:
    ttf = {}
    for f in family.fonts:
      if not os.path.exists(os.path.join(dirname, f.filename)):
        logging.warning(("METADATA.pb references a TTF file"
                         " that is missing: "
                         "'{}'").format(os.path.join(dirname, f.filename)))
        continue

      if font_key(f) in ttf.keys():
        # I think this will likely never happen. But just in case...

checks.check_that_glyph_names_do_not_exceed_max_length(fb, font)

##########################################################
## Metadata related checks:
##########################################################
    skip_gfonts = False
    is_listed_in_GFD = False
    metadata = os.path.join(family_dir, "METADATA.pb")
    if not os.path.exists(metadata):
      logging.warning(("{} is missing a METADATA.pb file!"
                       " This will disable all Google-Fonts-specific checks."
                       " Please considering adding a METADATA.pb file to the"
                       " same folder as the font files.").format(filename))
      skip_gfonts = True
    else:
      family = get_FamilyProto_Message(metadata)
      if family is None:
        logging.warning("Could not load data from METADATA.pb.")
        skip_gfonts = True
        break

      fb.default_target = metadata

      checks.check_METADATA_Ensure_all_TTF_references_are_valid(fb, family)
      checks.check_METADATA_Ensure_designer_simple_short_name(fb, family)
      is_listed_in_GFD = checks.check_family_is_listed_in_GFDirectory(fb,
                                                                        family)
      checks.check_METADATA_Designer_exists_in_GWF_profiles_csv(fb, family)
      checks.check_METADATA_has_unique_full_name_values(fb, family)
      checks.check_METADATA_check_style_weight_pairs_are_unique(fb, family)
      checks.check_METADATA_license_is_APACHE2_UFL_or_OFL(fb, family)
      checks.check_METADATA_contains_at_least_menu_and_latin_subsets(fb,

## Step 1: Cross-family tests
##         * Validates consistency of data throughout all TTF files
##           in a given family
##         * The list of TTF files in infered from the METADATA.pb file
##         * We avoid testing the same family twice by deduplicating the
##           list of METADATA.pb files first
###########################################################################

  metadata_to_check = []
  for target in fonts_to_check:
    metadata = os.path.join(family_dir, "METADATA.pb")
    if not os.path.exists(metadata):
      logging.error("'{}' is missing"
                    " a METADATA.pb file!".format(target))
    else:
      family = get_FamilyProto_Message(metadata)
      if family is None:
        logging.warning("Could not load data from METADATA.pb.")
      elif family not in metadata_to_check:
        metadata_to_check.append([family_dir, family])

  for dirname, family in metadata_to_check:
    ttf = {}
    for f in family.fonts:
      if font_key(f) in ttf.keys():
        # I think this will likely never happen. But just in case...
        logging.error("This is a fontbakery bug."
                      " We need to figure out a better hash-function"
                      " for the font ProtocolBuffer message."
                      " Please file an issue on"
                      " https://github.com/googlefonts"
                      "/fontbakery/issues/new")

monospace_detected)

##########################################################
## Metadata related checks:
##########################################################
    skip_gfonts = False
    is_listed_in_GFD = False
    metadata = os.path.join(family_dir, "METADATA.pb")
    if not os.path.exists(metadata):
      logging.warning(("{} is missing a METADATA.pb file!"
                       " This will disable all Google-Fonts-specific checks."
                       " Please considering adding a METADATA.pb file to the"
                       " same folder as the font files.").format(filename))
      skip_gfonts = True
    else:
      family = get_FamilyProto_Message(metadata)
      if family is None:
        logging.warning("Could not load data from METADATA.pb.")
        skip_gfonts = True
        break

      fb.default_target = metadata

      checks.check_METADATA_Ensure_designer_simple_short_name(fb, family)
      is_listed_in_GFD = checks.check_family_is_listed_in_GFDirectory(fb,
                                                                        family)
      checks.check_METADATA_Designer_exists_in_GWF_profiles_csv(fb, family)
      checks.check_METADATA_has_unique_full_name_values(fb, family)
      checks.check_METADATA_check_style_weight_pairs_are_unique(fb, family)
      checks.check_METADATA_license_is_APACHE2_UFL_or_OFL(fb, family)
      checks.check_METADATA_contains_at_least_menu_and_latin_subsets(fb,
                                                                     family)

def family_metadata(family_directory):
  from google.protobuf import text_format
  from fontbakery.utils import get_FamilyProto_Message

  if family_directory:
    try:
      pb_file = os.path.join(family_directory, "METADATA.pb")
      if os.path.exists(pb_file):
        return get_FamilyProto_Message(pb_file)
    except text_format.ParseError:
      return None

def family_metadata(family_directory):
  from fontbakery.utils import get_FamilyProto_Message

  if family_directory:
    pb_file = os.path.join(family_directory, "METADATA.pb")
    if os.path.exists(pb_file):
      return get_FamilyProto_Message(pb_file)